Composite of aluminum material and synthetic resin molding and process for producing the same

ABSTRACT

A process for producing a composite of aluminum material and synthetic resin molding with high efficiency; and a stable fast composite exhibiting high peeling resistance and large mechanical strength. The process is characterized in that aluminum material ( 1 ) is anodized in electrolytic bath of phosphoric acid or sodium hydroxide to thereby form anodic oxidation coating ( 2 ) provided with innumerable pores ( 3 ) having a diameter of 25 nm or more made open in the surface thereof is formed thereon, and a synthetic resin mold ( 6 ) is coupled with the anodic oxidation coating ( 2 ) in such a condition that the portion ( 6   a ) of the synthetic resin molding ( 6 ) is intruded or anchored in the innumerable pores ( 3 ) of the anodic oxidation coating ( 2 ). By this process, composite (P) with the above properties can be easily obtained.

TECHNICAL FIELD

The present invention relates to a stable and fast composite which isexcellent in peel strength by strongly coupling a synthetic resinmolding with an aluminum material, and a process for production thereof.

BACKGROUND ART

It has been hitherto disclosed as an invention on an aluminum composite,for example, the Japanese Unexamined Patent Publication No. 05-05179,which discloses such a process for producing an aluminum composite thata particulate of polytetrafluoroethylene is electrochemically orchemically adsorbed on a surface of an anode-oxidized coated film ofaluminum or an aluminum alloy, and after dried, it is lapped with anopposite material, so that an aluminum composite which is excellent infriction and wear property and baking resistance is produced. Thisdisclosed reference is, in other words, the publication disclosing theinvention of a surface treating method for treating the surface ofaluminum in which the lubricant film is formed on the surface of theanodic oxidation coating of the aluminum.

Further, there is disclosed in the Japanese Unexamined PatentPublication No. 2001-172795, the inventions on an aluminum compositereduced in discharging gas and particles and improved in insulation andcorrosion resistance and on a method for surface-treating the aluminumcomposite, in which a polysilazane solution is applied on the surface ofthe aluminum composite with an acidic oxide film formed on a substrateformed from aluminum or aluminum alloy, dried and baked to surface-treatthe composite.

Thus, those inventions disclosed in these cited references are directedto a method for surface-treating the aluminum material, and are notdirected to such a composite of aluminum material formed from aluminumor aluminum alloy raw material by applying it to an anodic oxidizationtreatment, and an synthetic resin molding that is strongly bondedtogether, and a process for producing the composite, which are thepurpose of the present invention as will be described below in detail.

In the meantime, the conventional production of a composite of aluminummaterial and a synthetic resin molding is not only troublesome, but alsothere is not obtained a safe and fast composite which is large in amechanical strength and of which the overall surfaces of the twoconstructional members thereof are bonded together.

Further, it has been hitherto carried out that using a conventionalmetal mold for insert molding, a composite is produced in such a mannerthat a portion of a metallic component made of iron or steel is insertedinto the cavity of the metal mold, and while being held under thisinserted condition, molten synthetic resin is injected into the cavity,so that a composite in which the portion of the metal component isinserted in a synthetic metal molding in a predetermined shape isproduced.

However, in the case where the metallic component is made of aluminumraw material, because the surface thereof is the metallic one ofaluminum or an aluminum alloy, and because coefficient of linearexpansion of the synthetic resin to be molded by the insert molding andthat of the aluminum are much different, it is difficult to produce acomposite thereof.

Now, as generally known, production of assembled products of variouselectric and electronic parts of personal computers, digital cameras,pocket telephones, fittings for chassis or the like, electric andelectronic containers such as casings or covers containing electricapparatus or electronic apparatus, and various kinds of parts forbuildings, various kinds of parts such as ornamental parts for fittingto the inside or outside of motorcars, is performed by assembling analuminum work prepared by previously press working a sheet of aluminuminto a desired shape such as a predetermined case or cover, and asynthetic resin molding together by various assembly means to produce acomposite. More in detail, some examples of the conventional compositesare produced as follows. For instance, it is produced by stacking apress-worked aluminum plate and a synthetic resin mold each otherthrough a pressure sensitive adhesive double coated tape. Alternatively,it is produced in such a process that a worked aluminum plate having alarge number of caulking claws arranged on both side edges of thealuminum plate is manufactured, and a synthetic resin mold is placed onthe aluminum plate, and in this state, the large number of the claws areinwardly bent on the surface of the synthetic resin mold. Further,alternatively, in stead of assembling them together by caulking of thelarge number of the claws, it is produced by fastening the mutuallystacked members together using screws.

A composite as shown in FIG. 20 is a cover for a switch box showing oneexample of the former. This composite is produced as follows. Namely,after the container of a worked aluminum A shaped by press working asheet of aluminum into the cover having at its center a hole for passingdistributing electric wires, and a synthetic resin molding B formed byan injection molding process are prepared separately, the rear surfaceof the aluminum cover A and the flat surface of the synthetic resin moldB are overlapped with each other through a pressure sensitive adhesivedouble coated tape C and adhered together by pressing, so that acomposite thereof is produced.

In addition, in the case of fitting synthetic resin made studs, which isused for mounting a chassis for an electric apparatus, and to the innersurface of the aluminum cover or case, so as to produce a composite ofthe two component, it is a conventional method that the two componentsare adhered together through an adhesive.

Thus, the conventional processes for production of composites eachcomposed of an aluminum material and a synthetic resin mold requiressuch steps that the formed aluminum plate by press working and thesynthetic resin mold are respectively made previously, and the twocomponents are then assembled together by the above mentioned variousjoining means, so that it takes much time and troublesome in productionthereof, resulting in lowering the production efficiency and increasingthe manufacturing costs. Further, among the composites produced, theones produced using the pressure sensitive adhesive double coated tapeor an adhesive agent, there is brought about deterioration of thequality of the adhesive agent with the lapse of time and weakening thestrength thereof. And, the ones assembled by caulking or screwing themtogether are not bonded together extensively or completely between themutually opposite surfaces thereof, so that there is brought about suchproblems that the mechanical strength of the composites is weak as awhole, and is unreliable against vibrations and impact, so that a stableand fast composites can not be obtained.

Further, in the case of producing the composite produced by a so-calledcasting using a metal mold for injection-molding, in which a portion ofthe aluminum material is inserted into the cavity of the metal mold, sothat there is brought about such inconveniences that a tensile strengthof the joint portion between the synthetic resin molding and theinserted portion of the aluminum material is weak and is peeled fromreach other by vibrations and impact to become shaky.

Accordingly, in view of the above-mentioned conventional problems, thepurpose of the present invention is to produce at high efficiency andeconomically a stable and fast composite which, without requirement ofthe pressure sensitive adhesive doubled coated tape, adhesives, bindingmembers such as a screw and a step of assembling of the two members, themutually opposite surfaces of an aluminum material of any desired shapeand size made of aluminum or aluminum alloy and a synthetic resin moldof any desired shape and size are bonded together strongly over thewhole surfaces thereof to become large in peel resistance.

To achieve this purpose, various tests, researches and trial and errorshave been carried out, and as a result, the inventors have found thatwhen an aluminum raw material is subjected to an anodic oxidizationtreatment so that an aluminum material provided with an anodic oxidationcoating having a predetermined diameter of pores may be formed, therebya synthetic resin material is very strongly coupled with the anodicoxidation coating of the aluminum material, so that a composite which isvery large in peel resistance can be obtained.

More in detail, it has been found out, in the course of tests andstudies, that in the test case where the surface of the aluminum rawmaterial was subjected to an anodic oxidization treatment to be formedwith the anodic oxidation coating in a sulfuric acid bath with analternating current electrolysis or a direct current electrolysis, therewas obtained the anodic oxidization coating provided with an innumerablenumber of surface opening pores of which the diameter of the majority ofthe surface open pores was about 10 nm. When the aluminum materialhaving the anodic oxidation coating was then placed in a recess made inone of metal molds for injection molding, and the other metal moldprovided with a cavity formed in a predetermined shape was closed, andmolten synthetic resin was injected into the cavity to be filled thereinunder pressure, and after cooling, the closed metal molds were opened,and a resultant composite product was taken out.

When a tensile strength was applied to the synthetic resin mold of thecomposite, the synthetic resin molding was peeled off easily from theanodic oxidation coating of the aluminum raw material due to a smalltensile strength. When the anodic oxidation coating was observed inorder to study the cause thereof, it has been found that the surfaceopen pores thereof are too small that the molten synthetic resin can notbe invaded into the pores. Now, instead of the sulfuric acid bath, usingan oxalic acid bath, a phosphoric acid bath, a sodium hydroxide bathetc, electrolysis by a direct current was carried out and there wereobtained respective aluminum materials having respective anodicoxidation coatings, and for the respective aluminum raw materials, theywere subjected to the foregoing injection molding using the foregoingmetal mold for injection molding, so that respective composites in whichthe synthetic resin moldings were coupled with the respective anodicoxidation coatings of the respective aluminum raw materials. When thetensile strength was applied to teach of the respective synthetic resinmoldings thereof, the composite using the oxalic acid bath was peeledeasily. However, the composite using the phosphoric acid bath and thesodium hydroxide bath, the synthetic resin molds of the respectivecomposites were not peeled off even by a very large tensile strength.Now, after the synthetic resin molds of the respective composites werecut off from the respective anodic oxidation coatings thereof, it wasobserved that the innumerable pores of the respective anodic oxidationcoatings were filled with solidified synthetic resin. Thus, as a resultof the comparative tests, it has been found out that if molten resin isinvaded into at least most of the innumerable pores, not to mention allof the pores, in the time of the molding process, molten resin isinvaded into these pores, and as a result of the solidification, acomposite is produced in which the synthetic resin molding is coupledstrongly with the aluminum raw material in such a condition thatsynthetic resin molding is intruded into the pores.

DISCLOSURE OF THE INVENTION

The present invention has been made in view of the above mentionedfindings, and provides a composite of an aluminum material and asynthetic resin molding characterized in that part of the syntheticresin molding is coupled with an anodic oxidation coating of thealuminum material in such a condition that it is intruded into theinnumerable pores having a diameter of 25 nm or more innumerably madeopen in the surface of the anodic oxidation coating.

This composite is large in the tensile strength of the synthetic resinmolding resisting against peeling from the aluminum material and isstable and fast.

Further, the present invention is directed to a process for producing acomposite of an aluminum material and a synthetic resin molding, and ischaracterized in that it comprises the steps: (a) soaking an aluminumraw material in a phosphoric acid or sodium hydroxide electrolytic bath,and applying to the surface thereof an anodic oxidization treatment by adirect current electrolysis to form an anodic oxidation coating havinginnumerable pores having 25 nm or more in diameter made in the surfacethereof, and (b) then placing a portion or whole of the aluminummaterial with the anodic oxidation coating in a cavity made in apredetermined shape in a metal mold, and injecting molten syntheticresin toward a portion or whole of the exposed surface of the anodicoxidation coating in the cavity so that the molten synthetic resin mayinvade into the innumerable pores and also may be filled in the cavityunder pressure to be molded.

According to this production process, the conventional assemblingcomponents or members and troublesome assembling works are disused, andthe above-mentioned stable and fast composite can be obtained at a highefficiency and economically. When a tensile strength of each of thesynthetic resin moldings of some composites produced according to thepresent invention was measured by a tensile tester, composites producedusing the phosphoric acid, the tensile strength of the synthetic resinsagainst the phosphoric acid anodic oxidation coatings thereof was 20 Kgfeven the minimum, and the tensile strength thereof against the sodiumhydroxide anodic oxidation coatings was 20 Kgf even the minimum, andthus, there were obtained the stable and fast composites that are largein tensile strength.

Further, in the case of the anodic oxidization treatment by phosphoricacid in the process for production of the foregoing composite accordingto the present invention, it is preferable to treat under the followingconditions. Namely, the aluminum raw material is anodized in aphosphoric acid bath comprising an aqueous solution of phosphoric acidhaving the concentration range of 15-40% and the temperature range of10-30° C., by applying direct current electrolysis for 5-25 minutes, ata voltage in the range of 20-100 V, and at a current density in therange of 0.5-2 A/dm², thereby an anodic oxidation coating havinginnumerable pores that are made open in the surface and have a diameterof 25 nm or more can be formed.

On the other hand, in the case of the anodic oxidization treatment bysodium hydroxide, it is preferable to treat under the followingconditions. Namely, the aluminum raw material was anodized in a bathcomprising an aqueous solution of sodium hydride having theconcentration range of 0.05-0.3 mol, and the temperature range of 10-30°C., by applying a direct current electrolysis for 5-25 minutes, at avoltage in the range of 15-45 V, and at a current density in the rangeof 0.5-3 A/dm², thereby an anodic oxidation coating having innumerablepores that are made open in the surface and have a diameter of 25 nm ormore can be formed.

In order to obtain the foregoing large tensile strength, it is notnecessary that the diameter of all of the pores made open in the surfaceof the aluminum raw material has to be 25 nm or more, and if thediameter of the majority of the pores, specifically, about 85% or moreof all the pores is 25 nm or more, a stable and fast composite havingthe foregoing large tensile strength can be obtained.

Incidentally, if the anodic oxidization treatment by the phosphoric bathor sodium hydroxide bath is carried out in the other anodic oxidizationconditions than the foregoing respective anodic oxidization treatments,there is such inconveniences that destruction of the anodic oxidationcoating is progressed by rising of the bath temperature, etc, andpowders are gushed out or become like a film covering the anodicoxidation coating, so that bonding of the anodic oxidation coating ofthe aluminum material to the synthetic resin molding becomes impossible.

For production of the composite according to the present invention, ametal mold for injection molding, a metal mold for insert-molding, aco-extruding machine, a jig containing an electromagnetic inductionheater may be employed.

Additional disclosure of the present invention will be made clear withreference to the below-mentioned embodiments of the present inventionwith reference to the accompanying drawings.

BRIEF DESCRIPTON OF THE DRAWINGS

FIG. 1 is a schematic vertical section, partly omitted, of an aluminummaterial of which the surface is formed with an anodic oxidation coatingby an anodic oxidization treatment on the surface of an aluminum rawmaterial in order that the aluminum raw material may be adapted to usefor producing a composite of the aluminum material and a synthetic resinmolding according to the present invention.

FIG. 2 is an electron microscopic photograph showing the surface of theanodic oxidation coating of the aluminum material as shown in FIG. 1.

FIG. 3 is a vertical section for explaining one embodiment of a processfor producing a composite according to the present invention in whichthe aluminum material formed with the anodic oxidation coating as shownin FIG. 1 is placed in metal molds, and a synthetic resin molding iscoupled with a portion of the anodic oxidation coating in the conditionthat it intruded therein.

FIG. 4 is a vertical section for explaining another embodiment of aprocess for producing a composite according to the present invention inwhich the aluminum material formed with the anodic oxidation coating asshown in FIG. 1 is placed in the metal molds, and a synthetic resinmolding is coupled with the whole surface of the anodic oxidationcoating in the condition it is intruded therein.

FIG. 5 is a schematic vertical section of a portion of a composite ofthe present invention produced by the embodiment as shown in FIG. 1.

FIG. 6 is a schematic section of a portion of a composite of the presentinvention in which the remaining portion of the anodic oxidation coatingthat is not overlapped with the synthetic resin molding of the compositeof the present invention as shown in FIG. 5 is applied with a sulfuricacid anodic oxidation coating by an after-treatment.

FIG. 7 is a schematic vertical section of a portion of a composite ofthe present invention in which the remaining part of the anodicoxidation coating that is not overlapped with the synthetic resinmolding of the composite of the present invention as shown in FIG. 5 isapplied with a paint-coating by an after-treatment.

FIG. 8 is a rear view of one embodiment composite for using as a coveror container for a switch box that is produced according to a processfor producing a composite according to the present invention.

FIG. 9 is a side view of the composite as mentioned above.

FIG. 10 is a sectional view taken along the line A-A in FIG. 8.

FIG. 11 is a sectional view taken along the line B-B in FIG. 8.

FIG. 12 is a sectional view, partly omitted, of such a state of use ofthe composite of the present invention as shown in FIG. 8, that achassis for electronic apparatus is fixed thereto.

FIG. 13 is sectional side view of an important portion of part of amolding device for injection molding used as further another embodimentof a process for producing a composite according to the presentinvention.

FIG. 14( a)-(d) are sectional side views showing one embodiment ofproducing steps in producing a printed composite according to thepresent invention.

FIG. 15( a)-(d) are sectional side views showing another embodiment ofproducing steps in a process for producing a printed composite accordingto the present invention.

FIG. 16( a)-(d) are sectional side views showing further anotherembodiment of producing steps in producing a process for producing aprinted composite according to the present invention.

FIG. 17 is a vertical section of a further another embodiment of acomposite of the present invention produced by an insert-moldingprocess.

FIG. 18 is a sectional side view of a portion of a heating and pressingapparatus for showing a further another embodiment of a process forproducing a composite according to the present invention.

FIG. 19 is a perspective view of a composite produced by a furtheranother embodiment of a process for production of a composite accordingto the present invention.

FIG. 20 is a dissembled perspective view of a conventional compositeused for a cover for a switch box.

BEST MODE OF CARRING OUT THE INVENTION

The process for producing a composite of an aluminum material and asynthetic resin material according to the present invention isapplicable in stead of all of such conventional marketed compositesproduced by assembling an aluminum material having a desired shape and adesired size and a synthetic resin mold having a desired shape and adesired size, using the foregoing conventional techniques, as parts orfittings of electric apparatus and electronic apparatus like personalcomputers, pocket telephones, or the like, interior or exteriorequipments, parts of buildings, interior or exterior equipments of boatsand ships, aircraft, railroad rolling stock, motor vehicles, andornamental articles such as name plates, as produced using the foregoingconventional assembling techniques.

One embodiment of a process for producing a composite according to thepresent invention comprising, firstly, applying aluminum material rawmaterial formed in a desired shape, to an anodic oxidization treatmentto make aluminum material of which both surfaces are formed with ananodic oxidation coatings having innumerable pores of which at leastgreater part is 25 nm or more in diameter, and, secondly, injectingmolten synthetic resin toward the anodic oxidation coating of thealuminum material using an injection molding device. As the injectionmolding device, an injection-molding device mold and an insert moldingmachine, are generally used.

Here, the term “at least greater part” in the expression “at leastgreater part of the innumerable pores is 25 nm or more” means about 85%or more, not to mention all of the pores.

And, as composite, various kinds of composites can be considered, forexample, as mentioned below. Namely, an aluminum raw material in theshape of a plate, a solid one formed by bending the flat plate in two orthree dimensions by press-working, or a worked aluminum raw material inthe shape of a rod, column or tube and the like are used. And one sidesurface, both side surface or circumferential surface are formed withthe anodic oxidation coating depending on the varied shapes of therespective aluminum raw materials. The synthetic resin molding iscoupled with the part or the whole of at least one side surface of theanodic oxidation coatings thereof in such a condition that part of thesynthetic resin is intruded in the innumerable pores thereof, so thatthe respective composites are produced. Further, alternatively, thesynthetic resin mold is coupled, by the way as mentioned above, with thepart or whole of one side surface of the anodic oxidation coatingsformed on both side surfaces of the aluminum raw material, and the othersurface of the aluminum material is applied with printing, so that aprinted composite is produced. Furthermore, alternatively, the aluminummaterial with the anodic oxidation coatings on both sides thereof or thecircumferential surface thereof is used as an insert member, and usingan insert-molding device, a predetermined part of the insert memberthereof is embedded in and bonded strongly to a formed synthetic resinmold in the condition as mentioned above, so that a composite by aso-called insert-molding process is produced. Furthermore, a compositeproduced by boding an aluminum material and a synthetic resin moldingtogether by a heating and pressing process is produced as mentionedbelow.

Next, a basic process for producing a composite of an aluminum materialand a synthetic resin will be explained with reference to theaccompanying drawings.

1) Forming of an Anodic Oxidation Coating:

The purpose of the present invention can be achieved even by usingeither of aluminum or an aluminum ally as an aluminum raw material, butthe following will be explained about the case where aluminum is used asan aluminum raw material.

EXAMPLE 1

An aluminum raw material comprising a plate having about 1-2 mm inthickness was used as an aluminum raw material, and was washed with anabout 5% aqueous solution of phosphoric acid heated to 60° C. forcleaning the same, and was then soaked in a 20% aqueous solution ofnitric acid to be neutralized, and was then washed.

Next, it was used as an anode in a phosphoric acid bath having atemperature in the range of about 18-20° C. and containing an about 30%aqueous solution of phosphoric acid in concentration, while an aluminumplate or a lead plate was used as a cathode, and electrolysis carriedout for 20 minutes using a direct current and at a voltage in the rangeof 30 V-70 V, at a current density in the range of about 0.5-1 A/dm², sothat a porous anodic oxidation coating having a depth of about 1-1.5μwas formed on the surface of the aluminum plate. The anodic oxidationcoating, as well known, is composed of a porous layer of densely longand narrow pores made open in the surface and a thin minute insulationlayer from the bottom of the porous layer to the metallic surface in theplate, as well known.

And, the diameter of the almost all of the open pores made in thesurface as mentioned above was in the range of about 40-90 nm.

EXAMPLE 2

Instead of the phosphoric acid bath, using a sodium hydroxide bath, ananodic oxidation treatment was applied to the same aluminum raw materialplate as that used in Example 1. Namely, as an electrolytic bath, thatof a 0.2 mol aqueous solution of sodium hydride and with a temperaturein the range of about 18-20° C. was used, and an electrolysis wascarried out by a direct current process for about 20 minutes, at avoltage of 25V, at a current density of about 0.5 A/dm², and thereby aporous anodic oxidation coating of which almost all of the open poresare about 30-50 nm in diameter was formed.

The respective aluminum material plates formed with the respectiveanodic oxidation coatings thereon thus produced in FIG. 1 and FIG. 2were then washed with an aqueous solution of nitric acid, and thereafterdried by a hot blast.

FIG. 1 is a schematic section of part of a plate-shaped aluminummaterial A′ formed with the anodic oxidation coating on both sidesurfaces thereof produced in Example 1 or Example 2(hereinafter simplyreferred to “as an anodic oxidization treated plate A′”). The thicknessof the anodic oxidization treated plate A′ is 1 mm, but the intermediateportion thereof is omitted in the same Figure. A reference symbol 2denotes the anodic oxidation coating, 2 a denotes the porous layerhaving innumerable pores 3 and 2 b denotes the insulation layer. Asymbol D indicates the diameter of the pore 3. FIG. 2 is an electronmicroscopic photograph showing the surface of the phosphoric acid anodicoxidation coating 2 of the anodic oxidation treated plate A′ produced inExample 1.

And, it has been recognized that the anodic oxidization treated plate Acomprising the porous anodic oxidation coating 2 having the innumerablepores in which at least almost all thereof is 25 nm or more in diametercan be obtained

Further, as is clear from comparison between Example 1 and Example 2, ithas been found that when the electrolysis time is the same, thephosphoric acid bath is more advantageous than the sodium hydroxidebath, because the larger diameter of the pores can be obtained in theshorter time.

Furthermore, when the electrolysis time used in Example 1 was shorten to3 minutes, an anodic oxidation coating plate in which most of the poresformed therein were in the rang of 25-30 nm in diameter was obtained.

Furthermore, incidentally, when the electrolysis time used in Example 1and Example 2 was elongated to 30 minutes, powders were gushed out atthe surface of the anodic oxidation coating and is grown to a film andcovers or fills in the innumerable pores, and consequently hindersmolten synthetic resin from invading into the pores, so that the strongbonding of the anodic oxidation coating thereof with the synthetic resinmolding was made impossible. Conversely, when the electrolysis time usedin Example 1 was shorten to 1 minute, and that used in Example 2 wasshortened to 3 minutes, the pores having a diameter of 25 nm or more arehardly obtained, and molten synthetic resin was hardly invaded into thepores, so that the strong bonding of the anodic oxidation coating withthe synthetic resin mold was not obtained.

2) Production of a Composite by an Injection Molding:

The anodic oxidization treated plate A′ according to of the presentinvention produced as mentioned above and as shown in FIG. 1 in whichmost of the pores 3 of the anodic oxidation coating 2 are 25 nm or morein diameter was fitly mounted in a metal mold for injection molding, forinstance, a mold for in-molding and molten synthetic resin is injectedinto a desired-shaped cavity of the metal mold so as to be invaded intothe innumerable pores and be filled in the cavity under pressure forforming the synthetic resin molding having a predetermined shape, and,from this condition, the metallic mold is cooled to be solidified, andthus there can be produced a composite of the present invention in whichthe synthetic resin molding is so strongly coupled with the anodicoxidation coating 2 of the aluminum treated plate A′ that part of thesynthetic resin mold is intruded in the innumerable pores 3, 3, . . . .Embodying examples according to the present invention will be explainedwith reference to FIG. 3 and FIG. 4.

The embodying example as shown in FIG. 3 used a pair of metal molds forinjection molding 4. Namely, there was used such an injection moldingthat the anodic oxidation treated plate A as shown in FIG. 1 is placedon the upper surface of one side metal mold 4 a thereof, and the lowersurface of the other side metal mold 4 b which faces the metal mold 4 ais formed with a recessed space for housing the anodic oxidizationtreated plate A′ and with such a cavity 5 in a predetermined shape thatis positioned above the recessed space and faces a partial area of thesurface of the anodic oxidation coating 2 of the anodic oxidizationtreated plate A′ housed therein, for instance, the central area of thesurface of the coating 2. Under the closed condition of the upper andlower metal molds 4 a and 4 b as shown in FIG. 3, molten synthetic resinsupplied from the outside is injected into the cavity 5 through a sprue4 c from a pinpoint gate 4 d and is filled in the cavity 5 underpressure. Whereupon, part of the molten synthetic resin is forciblyinvaded into the faced innumerable pores 3 of the anodic oxidationcoating 2, and at the same time the remainder greater part of the moltensynthetic resin is filled in the cavity 5. Next, the molten syntheticresin is solidified by cooling water passing through the metal molds,though not shown. Thus, A composite P of an anodic oxidization treatedplate A′ and a synthetic resin molding 6 as shown in FIG. 5 is obtained.The composite P as shown in the same Figure, is obtained as a producthaving a large peel strength in such a coupled condition that the lowerportion 6 a of the synthetic resin mold 6 is intruded in the innumerablepores 3 of the anodic oxidization treated plate A′.

In the process for production of this composite, it is preferable thatthe metal molding machine 4 is provided with a heater and the abovementioned injection molding process is carried out by heating the moldsby the heater. Thereby, the mutually coupling of the molten syntheticresin and the heated anodic oxidization treated plate A′ can befacilitated. And, it is sufficient that a molding pressure at the timeof the injection molding is about 700 Kg or more. Normally, it is ingeneral and preferable that the injection molding work is carried out ata temperature in the range of 90-180° C. and at a molding pressure inthe range of 700-1200 Kg.

As for synthetic resin materials, various kinds such as PP. PE, PBT,ABS, PPS etc. may be used, and it has been confirmed that, regardless ofkinds thereof, there can be obtained the composite P in which thesynthetic resin mold 6 and the anodic treated plate A are stronglybonded together.

In stead of the production of the composite P in which the syntheticresin mold 6 is coupled with the portion of the surface of the anodicoxidation coating 2 of the anodic oxidization treated plate A′, acomposite in which a synthetic resin mold is coupled with a wholesurface of the anodic oxidation coating of the anodic oxidizationtreated plate A′ may be produced.

FIG. 4 shows one example of producing the composite as mentioned above.

Namely, metal molds for injection molding 4′ as shown in FIG. 4 is used.A metal mold on one side thereof having the same in construction as theforegoing metal mold 4 a is used, but as the other metal mold facing themetal mold 4 a there is used a metal mold 4 b′ that is formed, at itslower surface, with a recessed space for housing the anodic oxidizationtreated plate A′ placed on the metal mold 4 a and such a cavity 5′ in apredetermined shape that faces the whole of the surface of the anodicoxidation coating 2 of the anodic oxidization treated plate A′. In themutually closed condition of both the metal molds 4 a and 4 b′, moltensynthetic resin is injected into the cavity 5′ through pinpoint gate 4d, so that there is obtained a composite P′ in which the whole area ofthe lower portion 6 a′ of a synthetic resin mold 6′ is strongly coupledwith the whole area of the surface of the anodic oxidation coating 2 inits intruded condition.

Further, it is of course that another composite may be produced by sucha process that, though not shown, a metal mold formed therein withplural number of cavities in a desired shape is used as a female mold,and a metal mold formed therein with plural number of sprues forindividually connected to the respective cavities is used as a malemold, and molten synthetic resin is injected through the respectivesprues into the respective cavities, so that there is obtained acomposite in which plural number of mutually independent synthetic resinmoldings are coupled in their intruded condition with the surface of theanodic oxidation coating of the anodic oxidization treated plate.

Furthermore, in the case of the anodic oxidization treated plate A′formed on its both sides with the anodic oxidation coatings 2 and 2, asmentioned above, a composite in which the synthetic resin molding iscoupled with both the coating surfaces may be produced.

Furthermore, it has been recognized in general that when a bondstrength, that is, a tensile strength using a tensile tester is measuredon the composite produced by coupling the synthetic resin mold with theanodic oxidation coating using the phosphoric acid bath, and thecomposite produced by coupling the synthetic resin mold with the anodicoxidation coating using the sodium hydroxide bath, the compositeproduced using the anodic oxidization treated plate formed using thephosphoric acid bath is larger in tensile strength than the compositeproduced using the anodic oxidization treated plate formed using thesodium hydroxide bath. Furthermore, it has been confirmed that theanodic oxidization treated plate with the sodium hydroxide bath has thetensile strength of at least 20 Kgf, and the anodic oxidization treatedplate with the phosphoric acid plate has the tensile strength of atleast 30 Kgf.

3) After-Treatment:

The composite P in which the synthetic resin mold 6 is coupled with theportion of the anodic oxidation coating 2 as shown in FIG. 2 may be aproduct as it is. However, the respective anodic oxidation coatings 2formed using the phosphoric acid bath and the sodium hydroxide bath arecomparatively weak in an electrical insulation and an anti-corrosionproperties, and therefore it is preferable that an after-treatment isapplied to the portion of the surface of the anodic oxidation coatingthat is not overlapped with the synthetic resin molding and is exposedto the air. As an after-treatment, it is preferable that a paint coatingprocess or a process for forming an anodic oxidation coating formedusing a sulfuric acid bath is carried out, and, as desired, a sealingtreatment on the sulfuric acid coating is carried out, and, if needed, acoloring treatment for putting in a desired color is applied thereto forobtaining a product that is excellent in electric insulation propertyand anticorrosion property, and beautiful in appearance.

FIG. 6 shows a composite P1 which is one example obtained by such anafter-treatment that after the composite P as shown in FIG. 5 isproduced, such an anodic oxidation coating area that is around thesynthetic resin molding 6 and is not overlapped with the same and isexposed to the air is formed with an anodic oxidation coating 2′ by thesulfuric acid. Further, if necessary, a well known sealing treatment isapplied to the coating 2′. The sulfuric acid anodic oxidation coating 2′is in general that the pores made open in the surface thereof is assmall as 10 nm in diameter and 2-10μ in depth, and therefore, acomposite P′ that is excellent in electric insulation and anti-corrosionproperties is provided. In order to provide the said coatings 2′, thecomposite P as shown in FIG. 5 is subjected to cleaning or degreasing,neutralizing and chemical polishing, and thereafter it is anodized in asulfuric acid bath comprising, for instance, 10-20% aqueous solutions ofsulfuric acid, at temperature in the range of 15-25° C. and a directcurrent electrolysis is performed at a voltage of 10-25 V, at a currentdensity of 1-2/Adm². Thereafter, it is subjected to a sealing treatmentby any well known means such as a steaming treatment or boilingtreatment, or the like. For coloring, before the sealing treatment, itis colored by a well known coloring means, using, for instance, a dyebath at a temperature of 50-70° C. using any dye selected from variouskinds of dyes such as acid dyes, mordant dyes, basic dyes or the like.

In the course of that the composite is subjected to the various steps ofthe above-mentioned after-treatment process, the temperature differenceat the respective treatment steps is so large that is 100° C. at themaximum and 15° C. at the minimum. Therefore, at every time during thecourse of the each step of after-treatment, the composite is repeatedlygiven the heat shock caused by the rapid temperature difference.Accordingly, taking the difference in linear expansion between aluminumand synthetic resin into consideration, it is preferable, for syntheticresin materials to be injected for forming synthetic resin moldings bythe injection molding, to selectively use such synthetic resin that hasan elastic modulus which is able to absorb the linear expansion betweenthem, preferably, that of 10000 Mpa or below and that has a waterresisting property and a chemical resisting property. For such syntheticresins, Polybutylene terephthalate (PBT), polyethylene (PE),polypropylene (PP) and the like are optimum.

FIG. 7 shows a composite P2 produced by such an after-treatment that thearea portion of the anodic oxidation coating 2 that is not overlappedwith the synthetic resin mold 6 and thus is exposed to the air isapplied with a paint coating 7. In the case of paint coating, since theanodic oxidation coating 2 formed by the phosphoric acid bath or thesodium hydroxide bath has the innumerable pores 3, part of the paintcoating is invaded into these pores 3 and after dried at a normaltemperature or by heating, it is obtained as a stable and fast paintcoating 7 strongly adhered to the coating 2. Accordingly, it isunnecessary to apply a primer treatment to the anodic oxidation coatingbefore the paint coating treatment. The thickness of the paint coating 7is about 10 microns, but is not limited thereto.

As for paint coating materials, various kinds of synthetic resincoatings such as vinyl resin, acrylic resin, phenol resin, siliconeresin, urethane resin, etc are preferably used in general.

As is clear from the above, when the process for producing a compositeaccording to the present invention is used, in stead of production ofthe composites produced by integrally assembling the previously preparedaluminum raw materials in the shape of plate or a press-worked oneformed in any desired various shape and the previously preparedsynthetic resin moldings formed in any desired shape through variouskinds of interconnecting tools by the conventional producing process,the composites corresponding to the conventional composites can beproduced at a higher efficiency and economically through a less numberof steps for production. The process for producing the compositeaccording to the present invention is applicable to producing compositessuch as a container or cover for a switch box, containers or covers fordigital cameras, chassis for mounting electric parts or electronicparts, interior or exterior apparatus such as front panels, doorhandles, number plates of automobiles, etc, various kinds of buildingmaterials, various kinds of indoor or outdoor ornamental articles, etc.

FIGS. 8 to 11 show a composite P3 of the present invention correspondingto the conventional box cover as shown in FIG. 20. The composite P3 wasproduced according to the process for producing the composite of thepresent invention as mentioned above as follows.

Namely, an aluminum raw material work shaped into a cover casing andprovided with at its center a square hole a for passing distributingwires, by press-working of an aluminum raw material plate was treatedwith a phosphoric acid bath and under the same condition as the Example1, so that a cover-type aluminum material PA′ provided with an anodicoxidation coating 2 comprising innumerable surface-open pores of whichmost are 40 nm in diameter, in other words, an anodic oxidizationtreated cover PA′ was made, and thereafter it was set in a metal moldfor injection molding, and molten polyethylene resin was injected, sothat there was produced such a composite for a switch cover P3 thatcomprises a tubular molding 8 around the square hole a, four cylindricalmoldings 9 positioned in the vicinity of the four corners of the coverPA′ to be used as studs for mounting a chassis for installing electricand electronic equipments, and engaging moldings 10 formed to extendfrom the rear surfaces of the middle portions of the upper and lowerside walls of the cover PA′ to the ends of the upper and lower sidewalls for engaging with a case for a switch cover, with theabove-mentioned respective moldings are coupled with the innumerable thepores in their intruded condition. Symbol 11 denotes ribs formed inconformity with runners connecting to respective cavities for formingthe moldings 8-10 from a single gate made at the center of the injectionmolding metal mold. These ribs are useful for supporting the cover PA′from behind and reinforcing a mechanical strength thereof. Further, thewhole area of the portion of the cover PA′ that is not covered withthese moldings is formed with an anodic oxidation coating 2″by theafter-treatment using sulfuric acid bath.

Thus, as is clear from the composite of the present invention as shownin FIG. 8-FIG. 11, it has been recognized that after the aluminummaterial worked into a desired shape, in other words, an aluminum work,is formed with the anodic oxidation coating according to the presentinvention on the surface of the worked aluminum raw material, part ofthe synthetic resin molding having any desired shape and size is coupledin its intruded condition with at least one side surface of both theanodic oxidation coatings of the worked aluminum material by means ofthe injection molding process, so that a composite of the aluminummaterial and the synthetic resin molding strongly coupled together canbe obtained at a stroke.

In order to measure a tensile strength of the synthetic resin moldings8-10 on the anodic oxidization treated aluminum cover PA′ that is thecomposite P3 as illustrated, the composite was fixed in position, aninserting rod of a tensile tester was screwed into the cylindrical stud(10 nm in the outer diameter), and from this state, the tensile testerwas pulled upwardly and when the graduations of the tensile tester wasobserved, even an indicator needle was moved beyond 50 Kgf indicatingthe threshold value of the indicated graduations, the moldings 8-10 wassteady and thus a large peel strength thereof was demonstrated. When thesame tensile strength test as mentioned above was carried out on acomposite using the anodic oxidization treated aluminum material formedin Example 2, the crack was generated between the interfacial jointportions at the tensile strength of 45 Kgf, but a large peel strengthwas demonstrated.

According to the present invention as mentioned above, a furtheradvantageous effect is brought about as follows. Namely, heretofore, ithas been carried out that an aluminum plate was press-worked into acasing and metallic studs for installing electrical parts areelectrically welded to the rear surface of the casing. However, in thecase where the thickness of the aluminum plate is 0.6 mm or less, it isdistorted by the electric welding, and it is difficult that it ismerchandised as goods without distortion. Whereas, according to thepresent invention, the aluminum casing is formed with the anodicoxidation coating comprising the pores being 25 nm or more in diameteras mentioned above, and the studs of synthetic resin molds can becoupled with the rear surface of the aluminum casing by injectionmolding process, so that a composite without distortion is produced andit is possible that it is merchandised.

FIG. 12 shows such a state of use that a chassis is attached to theforegoing composite PA. Namely, it shows that the chassis d providedwith electronic equipments is placed on the studs 9 positioned at thefour corners thereof, and each screw f is screwed into the stud 9 tofasten the chassis d to these studs 9,9, . . . .

In producing the composite of the present invention by the metal moldfor injection-molding, it is preferable to produce it using a hot runnermold. FIG. 13 shows one example of the hot runner mold. In the drawing,symbol 40 denotes the mold. The mold 40 comprises an upper mold 40 b anda lower mold 40 a. The upper mold 40 b is provided with a sprue 40 c atthe center of the upper surface thereof and a right gate 40 d and a letgate 40 d on the right and left sides of the bottom surface thereof thatare positioned at the equal distances apart from the sprue 40 c. Arunner 40 e for connecting between the sprue 40 c and each of the gates40 d on the right and left, is formed as follows. Namely, The runner 40e is formed to be composed of a central passage 40 e 1 extendingdownwardly from the sprue 40 e, a horizontal passages 40 e 2 and 40 e 2extending right and left from the central passage 40 e 1, and verticallydownward right and left passages 40 e 3 and 40 e 3 extending downwardlyfrom the right and left horizontal passages 40 e 2 and 40 e 2 andconnecting to the right and left gates 40 d and 40 d. In addition, anozzle 13 containing a heater 12 therein is provided so as to surroundthe each vertically downward passage 40 e 3 and the each gate 40 d oneither side of the runner 40 e, and thus the runner 40 e is formed intoa hot runner.

Regarding the heater 12, either of a heating coil of an electric heaterconnecting to an outside power source and an electromagnetic inductionheating coil connecting to an outside high-frequency oscillator may beacceptable. In the drawing, 12 a denotes a leading wire connecting to anoutside high-frequency oscillator.

In addition, in the bottom surface of the upper mold 40 b, there is madea cavity 50 connecting to each gate 40 d on the right and left sidesthereof. In one example as shown in the drawing, the cavity 50 shows theone for forming a stud. On the other hand, in the upper surface of thelower mold 40 a, there is made a square mounting recess 40 a 1 formounting in place a bottom wall portion of a tray-shaped aluminummaterial PB formed with an anodic oxidation coatings 2 and 2 having aninnumerable pores 3 formed on both side surfaces of a case-shapedaluminum raw material according to the present invention, and further,in the bottom surface of the upper mold 40 b, there is made a squaregroove 40 b 1 for fitly inserting a square side wall PB2 upwardlyprotruding from the four sides of the bottom wall PB1 of the tray-shapedaluminum material PB. Since the mold 40 is symmetrical, the illustrationof the left-half important constructional portion thereof is omitted inthe Figure.

Thus, the upper mold 40 b and the lower mold 40 a are closed each otheras illustrated, and the outside high-frequency oscillator is driven tosupply the electric power to the heating coil 12, so that the aluminumwork PB is heated by an electromagnetic induction action, and, in themeantime, molten synthetic resin is injected into each cavity 50 fromeach gate 40 d on either side through the sprue 40 c and the runner 40 eby a heating cylinder of an injection molding device so as to form asynthetic resin molding 60 in the form of the stud. In this moldingprocess, the molten synthetic resin passing through the runner 40 e,before entering the cavity 50, is heated by the heating coil 12 built inthe nozzle 13 on either side, and thereby a good fluidity thereof iskept, so that the molten synthetic resin can be easily filled in thecavity 50 up to the corners thereof, and at the same time can be easilyinvaded into the innumerable pores on the opposite side of the cavity.Consequently, when the power supply is cut off, so that there isproduced a fast composite P4 in which the lower portion 60 a of thesynthetic resin molding of the stud 60 obtained as a result ofsolidification thereof by a cooling action of the lower mold 40 a isfully intruded in the pores. Further, the heating coil 12 is preferablymade of copper, and as desired, a pipe heating coil may be used forpassing cooling water and preventing generation of heat.

Production of the composite of the present invention using theplate-shaped aluminum raw material as a raw material includes also acase of production of composite printed on the surface thereof. Forproducing such a composite, it can be produced by the following threedifferent producing processes. This will be explained with reference toFIGS. 14-16.

Producing Process 1:

A composite is produced by the processing steps (a), (b), (c) and (d) asshown in FIG. 14. Namely, at the first step, forming both the surfacesof the plate-shaped aluminum raw material 1 with an anodic oxidationcoatings 2 and 2 as shown in the same Figure(a), then printing one sidesurface of both the anodic oxidation coatings 2 and 2 thereof in adesired ink by a desired printing means to form a printed surface asshown in the same Figure(b), then bending the same in second dimensionsor third dimensions, for instance, bending at the four sides thereof asillustrated, to be formed into a tray-shaped one, by press working asshown in the same Figure(c), and then strongly coupling a desired shapedsynthetic resin molding 6 with the anodic oxidation coating 2 on theopposite side to the printed surface in such a condition that a portion6 a thereof is intruded in the pores 3 thereof, by the injection moldingto produce a composite, as shown in the same Figure(d).

Producing Process 2:

A composite is produced by the processing steps (a), (b), (c) and (d) asshown in FIG. 15. Namely, at the first step, forming a printed surface14 on one side surface of a plate-shaped aluminum raw material 1 asshown in the same Figure(a), then bending the same in two dimensions orthree dimensions, for instance, bending the opposite both sides thereofinto a U-shaped frame, by press working as shown in the same Figure(b),then forming an anodic oxidation coating 2 of the present invention onthe other surface of the aluminum raw material as shown in the sameFigure(c), and then strongly coupling a desired shaped synthetic resinmolding 6 with the anodic oxidation coating 2 in such a condition that aportion 6 a thereof is intruded in the pores 3 thereof, by the injectionmolding to produce a composite, as shown in the same Figure(d).

Producing Process 3:

A composite is produced by the processing steps (a), (b), (c) and (d) asshown in FIG. 16. Namely, at the first step, forming a printed surface14 one side surface of a plate-shaped aluminum raw material 1 as shownin the same Figure(a), then forming an anodic oxidation coating 2 of thepresent invention on the other side surface thereof as shown in the sameFigure(b), then forming it in two dimensions or three dimensions, forinstance, bending at the four sides thereof as illustrated to be formedinto a tray-shaped one, by press working, as shown in the sameFigure(c), and then strongly coupling a desired shaped synthetic resinmolding 6 with the anodic oxidation coating 2 in such a condition that aportion 6 a thereof is intruded in the pores 3 thereof, by the injectionmolding to produce a composite, as shown in the same Figure(d).

Inks for using the printing and the printing means are selectivelyadopted from well known ones, and there are various kinds of inksprepared by dispersing pigments in vehicles such as synthetic resins,oils, solvents, etc and adding thereto auxiliary materials such aswaxes, driers, etc, and as kinds of printing inks, there arerelief-printing inks, planographic printing inks, rotogravure inks,ultraviolet radiation hardening type inks, and the like, and therespective printing inks suitable for respective types of printers areselectively used, and printing using these printing inks is applied toone side surface of an aluminum plate or the anodic oxidation coatedsurface of an anodic oxidization treated aluminum plate by means of aroll-coater printing, an offset printing, a flow-coater printing, etc,to form a printed face thereon. A thickness of the printed coat isgenerally obtained in the range of about 5-30μ.

As is easily understood from the above-mentioned process for producing acomposite, a composite comprising a cast mold that part of an aluminumraw material formed with an anodic oxidation coating on the surfacethereof is embedded strongly in the inside of a desired shaped syntheticresin molding can be produced by an insert molding, besides theabove-mentioned injection molding. Namely, though not illustrated, theabove-mentioned aluminum material formed with the anodic oxidationcoating is inserted into a cavity of a mold for insert molding, and, inthis state, molten synthetic resin is injected into the cavity to befilled in the cavity under pressure, so that there can be produced acomposite in which the part of the aluminum member is embedded, incoupled and intruded condition, in a synthetic resin molding and whichis large in tensile strength and stable and fast against impact andvibrations.

FIG. 17 shows one example of the composite produced by theabove-mentioned insert molding.

A composite P5 as shown in the same Figure has such a construction thata U-shaped frame member formed by bending a thick and long rectangularplate 10 into a U-shape in the transversal direction by press working isanodized to have an anodic oxidation coating 2 of the present inventionon the whole surface thereof, and parts of upper and lower arm portionsPC1 and PC1 of the anodic oxidization treated member PC are cast in athick and long rectangular synthetic resin mold 600 in a mutuallycoupled state, for serving as a handle. As is clear in the same Figure,a portion 600 a of the molding 600 is jointed to the surfaces of thearms PC1 and PC1 in the intruded condition, so that a composite that isstable and fast against impact and vibrations can be obtained.

The above-mentioned processes are intended to produce a composite at astroke by the injection molding. However, A composite of the presentinvention may be produced by such a process that a desired shapedsynthetic resin molding and an anodic oxidization treated aluminummaterial in a shape of plate or a press-worked one in other desiredshape are manufactured separately in advance and both the members aresubjected to a heating and pressing means.

FIG. 18 shows one example of an apparatus carrying out a process forproducing a composite using a heating and pressing means. In the sameFigure, Reference numeral 15 denotes a heating and pressing apparatus.The apparatus 15 comprises an electromagnetic induction heating device15A and a press head 15B which is moveable up and down by a pressurepiston (not shown). The electromagnetic induction heating device 15A isprovided with a flat-faced heating coil 12′ connecting to an outsidehigh-frequency oscillator 17 and built in a bottom wall 16 a of atray-shaped jig 16, and a recess portion 16 c formed by surrounding thebottom wall 16 a and a square peripheral wall 16 b of the jig 16 is soconstructed as to be acceptable an anodic oxidization treated aluminummaterial. The aluminum material PD as illustrated is previously preparedby such a working that the aluminum raw material 1 formed into atray-shaped one by press working and one side surface thereof is thenformed with a printed surface 14 and the other surface thereof is thenformed with an anodic oxidation coating 2. In the Figure, referencenumeral 18 denotes a jig setting plate placed on the working bench 19.

For producing a composite using the apparatus 15, the tray-shapedaluminum material PD is so placed on the bottom surface of the recessportion 16 c of the jig 16 that the rear surface having the anodicoxidation coating 2 thereof may be directed outwardly and a syntheticresin molding previously formed into a desired shape, as shown in theillustrated example, for example, plural number of synthetic resinmoldings 60′ each in the shape of a stud whose shape is the same as themold 60 as shown in FIG. 10 are placed at their predetermined positionson the horizontal bottom area and of the anodic oxidation coating 2, andin this state, the press head 15B is moved downwardly to press and thesemolds 60′ from above against the surface of the anodic oxidation coating2, and under the pressure the high-frequency oscillator 17 is actuatedand the electric current is supplied to the heating coil 12′, so thatthe aluminum material PE is heated by the induction heating thereof, andthe part of each stud molding 60′ that is brought in contact underpressure with the surface anodic oxidation coating 2 is molten, and themolten resin is invaded into the innumerable number of the pores 3.After a while, the electric the molten synthetic resin is cooled to besolidified, so that the part of the synthetic resin mold 60′ is coupledwith the anodic oxidation coating 2 in the condition that the it isintruded in the innumerable pores 3, so that there is obtained acomposite P6 in which the synthetic resin mold 60′ and the aluminummaterial PD are bonded together strongly.

When a further more specific embodiment of the process for production ofthe above-mentioned composite will be explained, the synthetic resinmolding 60′ is a tubular molding having a diameter of 6 mm made byinjecting synthetic resin, polyacetal (POM), the printed coat 14 appliedto the surface of the aluminum raw material is made by printing in inkcomposed mainly of alkyd resin paint and then baking. When the electricpower is supplied to the heating coil 12′ at a current density of 7A/dm², only for 1-12 seconds, the aluminum material PD is heated to180-190° C., so that the molding 60′ made of POM which is low in meltingtemperature is molten in a moment, and is invaded into the innumerablepores 3 of the anodic oxidation coating, and is solidified immediatelyafter cutting-off of the electric power supply. Thus, the composite canbe obtained for a short time and at a high efficiency.

Further, as the printed coat 14 is made of alkyd resin coating material,it is not damaged by the temperature range of the above. Furthermore, instead of the printed coat 14 using printing inks, it is possible to usevarious kinds of synthetic resin paints not containing pigments and formthe corrosion resisting coat as shown in FIG. 7. In either case, it isnecessary that the surface of the aluminum raw material or the surfaceof the anodic oxidation coating formed by anodic oxidization treatment,the same is coated with the heat resistant coating paint or printing inkthat can withstand the temperatures for melting synthetic resinmoldings.

The high-frequency oscillator 17 is variable to be in the range of 500W-50 Kw in output and 50 KHz-3 MHz in frequency. In the above-mentionedone embodiment of the heating and pressure means, it has been foundsuitable that that the output thereof is 2.5 Kw and the frequency is 900KHz.

FIG. 19 shows a composite P7 comprising a laminated pipe. The processfor producing the same is carried out as follows. The anodic oxidizationtreatment according to the present invention is applied to a thick andpipe-shaped aluminum raw material 100 formed by an extruder, so that ananodic oxidation coating 2 according to the present invention may beformed over the inner and outer circumferences and a total lengththereof to make a tubular aluminum material PE. Next, the tubularaluminum material PE is passed through a co-extruding molding machine,and molten synthetic resin is applied under pressure to the total lengthand circumferential surface of the anodic oxidation coating 2 formed onthe outer surface of the aluminum material, so that a synthetic resinmold that is formed into a tube having a desired thickness and in such acondition that part thereof is invaded into the innumerable pores 3 ofthe coating 2 is extruded together with the tubular aluminum material,and thus the composite P7 in the shape of the laminated pipe P7 isproduced. As illustrated, there is obtained the composite P7 composed ofthe mutually layered tubes strongly bonding together in such aconstructional state that part 6000 a of the tubular synthetic resinmold 6000 laid in an outer layer is intruded in the innumerable pores 3of the anodic oxidation coating 2 formed on the outer surface of thetubular aluminum material PE laid as an inner layer.

As is understood from the above, the aluminum raw material is limited toa straight plate one or a bent work thereof, and may be a tubular one asmentioned above, or, though not shown, any desired shaped one such as acircular or prismatic solid column, etc. The surface of any selected onethereof is formed with the anodic oxidation coating according to thepresent invention to make the anodic oxidization treated one, and thesynthetic resin mold in a desired form is coupled with the anodicoxidation coating of the aluminum material in the above-mentionedintruded condition, so that a composite strongly bonding the two memberstogether can be produced.

INDSTRIAL APPLICABILITY

As is clear from the above, the present invention is applicable to allof the industrial fields for producing a composite of an aluminummaterial and a synthetic resin mold such as buildings, boats and ships,aircraft, railroad rolling stock, etc, interior and exterior panels suchas interior door grips, exterior emblems, etc of automobiles, variouscasing or boxes and internal functional parts of personal computers,digital cameras, pocket telephones, PDA, electronic books, printers,televisions, audio devices, building materials, and others.

1. A composite of a worked aluminum material and a synthetic resinmolding, selected from the group consisting of polybutyleneterephthalate (PBT), polyethylene (PE), polypropylene (PP), ABS and PPSand polyacetal (POM), so constructed that the synthetic resin molding iscoupled with an anodic oxidation coating comprising innumerable poreshaving a diameter of from between 25 nm to about 90 nm and a depth frombetween about 1 μm to about 1.5 μm on the surface of the worked aluminummaterial, such that the synthetic resin molding is intruded in theinnumerable pores thereof and bonded together over a part or the wholesurfaces thereof as to have a vertical tensile strength from between 20Kgf/cm^2 to 45 Kgf/cm^2.
 2. The composite of claim 1 produced by aprocess comprising: (a) soaking an aluminum raw material in anelectrolytic bath of phosphoric acid or sodium hydroxide, the surface(s)thereof are subjected to an anodic oxidization treatment by directcurrent electrolysis to form an anodic oxidation coating comprisinginnumerable pores having a diameter of from between 25 nm to about 90nm, and a depth from between about 1 μm to about 1.5 μm; and (b) placingat least a portion of the worked aluminum material with the anodicoxidation coating in a cavity in a predetermined shape in a metal mold,and injecting molten synthetic resin toward the exposed surface of theanodic oxidation coating so that the molten synthetic resin, selectedfrom the group consisting of PBT, PE, PP ABS, PPS and POM, may beinvaded into the innumerable pores and also may be filled in the cavityunder pressure to be molded, so that a vertical tensile strength of thesynthetic resin a vertical tensile strength from between 20 Kgf/cm^2 to45 Kgf/cm^2.
 3. A composite produced by applying an after-treatmentprocess wherein after the composite is produced by the process of claim2, the synthetic resin mold is so coupled with the anodic oxidationcoating of the desired shaped aluminum material that part thereof isintruded in the innumerable pores, the remaining part of the anodicoxidation coating that is not overlapped with the synthetic resinmolding is applied with paint so that a corrosion resistant paintcoating is formed thereon.
 4. A composite produced by a process forproducing a composite wherein a phosphoric acid or sodium hydroxideanodic treated anodic oxidation coating formed on at least one surfaceof a worked aluminum material in a shape of a plate or bent into twodimensions or three dimensions by press working, is placed in a jigcontaining a heating apparatus in such a manner that the anodicoxidation coating may be directed upwards, and a synthetic resinmolding, selected from the group consisting of polybutyleneterephthalate (PBT), polyethylene (PE), polypropylene (PP), ABS, PPS andpolyacetal (POM), in a desired shape is placed on the anodic oxidationcoating and is pressed from above, and a contact portion of thesynthetic resin mold with the anodic oxidation coating surface is moltenby the heating apparatus under a condition that it is being contactedwith the surface of the anodic oxidation coating under pressure, so thatthe molten resin is invaded into the innumerable pores having a diameterof from between 25 nm to about 90 nm and a depth from between about 1 μmto about 1.5 μ, and in this state, an a vertical tensile strength frombetween 20 Kgf/cm^2 to 45 Kgf/cm^2.
 5. A composite produced by a processcomprising the steps: (a) forming an aluminum raw material into atubular one by an extruder, (b) applying an anodizing treatment to thetubular aluminum raw material to form an anodic oxidation coating withinnumerable pores having a diameter from between about 25 nm to about 90nm and a depth from between about 1 μm to at least 1.5 μm made on thesurface thereof may be formed, and (c) jointing a tubular-formedsynthetic resin molding, selected from the group consisting ofpolybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP),ABS, PPS and polyacetal (POM), having a desired thickness under pressurewith the circumferential surface and along the length direction of theanodic oxidation coating of the tubular aluminum material by aco-extruding molding machine, so that a composite in which the tubularaluminum material a vertical tensile strength from between 20 Kgf/cm^2to 45 Kgf/cm^2.
 6. The composite of claim 2, wherein the electrolyticbath is phosphoric acid or sodium hydroxide bath.
 7. The composite ofclaim 2, wherein the aluminum raw material is anodized in the phosphoricacid bath comprising 15-40% aqueous solutions of phosphoric acid inconcentration and having a bath temperature in the range of 10-30° C.and a direct current electrolysis is carried out for 5-25 minutes, at avoltage of 20-100V, at a current density of 0.5-2 A/dm², so that theanodic oxidation coating having the innumerable pores having a diameterof between about 30 nm to about 90 nm and a depth from between about 1μm to about 1.5 μm is formed.
 8. The composite of claim 2, wherein thealuminum raw material is anodized in a bath comprising 0.05-0.3 molaqueous solutions of sodium hydroxide, and having a bath temperature inthe range of 10-30° C., and a direct current electrolysis is carried outfor 5-25 minutes, at a voltage of 15-45V, at a current density of 0.5-3A/dm², so that the anodic oxidation coating having the innumerable poreshaving a diameter of between 25 nm to about 90 nm and a depth frombetween about 1 μm to about 1.5 μm is formed.
 9. The composite of claim2, wherein the molten synthetic resin is injected into the cavity of themetal mold under a heated condition of the metal mold.
 10. The compositeof claim 2, wherein the aluminum raw material in the shape of a plate ora worked aluminum raw material bent into two or three dimensions bypress working is used, and the synthetic resin mold is coupled with thepartial or whole surface of the anodic oxidation coating thereof byinjection molding.
 11. The composite of claim 2, wherein a portion of adesired-shaped aluminum material formed with the anodic oxidationcoating formed by the phosphoric acid or sodium hydroxide bath isinserted into a cavity of a metal mold for insertion molding, and inthis condition, molten synthetic resin is injected into the cavity andpart of the molten synthetic resin is invaded into the innumerable poresof the anodic oxidation coating and bonded together over a part or thewhole surfaces thereof, and in this state is filled in the cavity underpressure to be molded.
 12. The composite of claim 2 produced by aprocess comprising: coupling the synthetic resin mold with the anodicoxidation coating of the desired shaped aluminum material so that partthereof is intruded in the innumerable pores, the remaining part of theanodic oxidation coating that is not overlapped with the synthetic resinmolding is cleaned and is then subjected to an electrolysis using asulfuric acid bath, so that a corrosion resistant coating of alumite isformed.
 13. A composite of claim 2 produced by the process comprising:coupling the synthetic resin mold with the anodic oxidation coating ofthe desired shaped aluminum material that part thereof is intruded inthe innumerable pores, the remaining part of the anodic oxidationcoating that is not overlapped with the synthetic resin molding isapplied with paint so that a corrosion resistant paint coating is formedthereon; the synthetic resin having the elastic modulus that is able toabsorb the difference between the linear expansion of aluminum and thatof synthetic resin caused by a sudden temperature change is used as thesynthetic resin for forming a synthetic resin molding.
 14. The compositeof claim 1 produced by a process comprising: (a) applying anodicoxidization treatment to both side surfaces of a plate-shaped aluminumraw material by a phosphoric acid or sodium hydroxide bath to form ananodic oxidation coating on each surface comprising innumerable poreshaving a diameter of between about 25 nm to about 90 nm and a depth frombetween about 1 μm to about 1.5 μm, is formed, (b) forming a printcoating on one side surface of both the anodic oxidation coatings of theanodic oxidization treated aluminum material, (c) bending the same intosecond dimensions or third dimensions by press working, and (d) placinga portion or whole of the worked aluminum material with the anodicoxidation coatings in a cavity having a predetermined shape made in ametal mold, and injecting molten synthetic resin toward the exposed partor whole surface of the anodic oxidation coating in the cavity, so thatpart of the molten synthetic resin is invaded into the innumerable poresopen in the surface of the anodic oxidation coating and bonded togetherover a part or the whole surfaces thereof and also is filled in thecavity under pressure to be molded.
 15. The composite of claim 1produced by the process comprising: (a) forming a printed surface on oneside surface of a plate-shaped aluminum raw material, (b) bending thesame into two dimensions or three dimensions by press working, (c)applying an anodic oxidization treatment to the unprinted other sidesurface of the worked aluminum raw material by an electrolysis by aphosphoric acid or sodium hydroxide bath, so that the anodic oxidationcoating composed of innumerable pores having a diameter of between about25 nm to about 90 nm and a depth from between about 1 μm to about 1.5μm, is formed, and (d) placing the part or whole of the worked aluminummaterial with the anodic oxidation coatings in a predetermined shapedcavity of a metal mold, and injecting molten synthetic resin toward theexposed part or whole surface of the anodic oxidation coating in thecavity, so that part of the molten synthetic resin is invaded into theinnumerable pores open in the surface of the anodic oxidation coatingand bonded together over a part or the whole surfaces thereof and alsois filled in the cavity under pressure to be molded.
 16. The compositeof claim 1 produced by the process comprising: (a) forming a printedsurface on one side surface of a plate-shaped aluminum raw material; (b)applying an anodic oxidation treatment to the unprinted other sidesurface of the worked aluminum raw material by an electrolysis by aphosphoric acid or sodium hydroxide bath, so that an anodic oxidationcoating composed of innumerable pores between about 25 nm from about 90nm and a depth from between about 1 μm to about 1.5 μm, is formed, (c)bending the same into two dimensions or three dimensions by pressworking, (d) placing the part or whole of the worked aluminum materialwith the anodic oxidation coatings in a predetermined shaped cavity of ametal mold, and injecting molten synthetic resin toward the exposed partor whole of the anodic oxidation coating in the cavity, of that part ofthe molten synthetic resin is invaded into the innumerable pores open inthe surface of the anodic oxidation coating and bonded together over apart or the whole surfaces thereof and also is filled in the cavityunder pressure to be molded.
 17. The composite of claim 1 produced bythe process comprising: using a metal mold for injection moldingprovided with a heating apparatus surrounding a vertical passageconnecting to a sprue in the metal mold for injection molding and a gateconnecting to the lower end of the vertical.
 18. The composite of claim5, wherein the aluminum raw material is anodized in the phosphoric acidbath comprising 15-40% aqueous solutions of phosphoric acid inconcentration and having a bath temperature in the range of 10-30° C.,and a direct current electrolysis is carried out for 5-25 minutes, at avoltage of 20-100V, at a current density of 0.5-2 A/dm², so that theanodic oxidation coating having the innumerable pores having a diameterfrom between about 30 nm to about 90 nm and a depth from between about 1μm to about 1.5 μm is formed.
 19. The composite of claim 5, wherein thealuminum raw material is anodized in a bath comprising 0.05-0.3 molaqueous solutions of sodium hydroxide, and having a bath temperature inthe range of 10-30° C. and a direct current electrolysis is carried outfor 5-25 minutes, at a voltage of 15-45V, at a current density of 0.5-3A/dm², so that the anodic oxidation coating having the innumerable poreshaving a diameter of between 25 nm to about 90 nm and a depth frombetween about 1 μm to about 1.5 μm is formed.
 20. The composite of claim5, wherein the aluminum raw material in the shape of a plate or a workedaluminum raw material bent into two or three dimensions by press workingis used, and the synthetic resin mold is coupled with the partial orwhole surface of the anodic oxidation coating thereof by injectionmolding.